If "tail call recursion" means recursing as the last thing you do before returning, then he is saying to send a message as the last thing you do.
AKA send a message as a tail call instead of returning the value of that message.
If "tail call recursion" means recursing as the last thing you do before returning, then he is saying to send a message as the last thing you do.
AKA send a message as a tail call instead of returning the value of that message.